双频外差结合相位编码的相位解包裹方法

Phase unwrapping method based on dual-frequency heterodyne combined with phase encoding

为了使用高频条纹进行一次外差完成相位解包裹,实现高精度测量,提出了双频外差结合相位编码的相位解包裹方法。首先,用两组正弦条纹获得两个包裹相位,进行外差处理得到外差相位;其次,相位编码条纹得到条纹级次后对外差相位展开;最后,由连续的外差相位对两个包裹相位进行展开,用最高频率的连续相位求得物体的相位信息。实验结果表明:RMS误差为0.038 mm。双频外差合成的周期不需要覆盖整个视场,打破了传统双频外差方法对频率选择的限制,可以用更高频率的条纹进行高精度测量。克服了相位主值误差对使用更高频率条纹进行高精度测量的局限性。

In order to complete phase unwrapping with a heterodyne of high frequency fringe and achieve high accuracy measurement,a phase unwrapping method of dual frequency heterodyne combined with phase coding was proposed.Firstly,two wrapping phases were obtained by two sinusoidal stripes,and one heterodyne phase was obtained by heterodyne processing;Secondly,the phase coding fringe was used to obtain the fringe order,and the heterodyne phase was unwrapped by fringe order;Finally,the two wrapping phases were unwrapped by continuous heterodyne phases,and the phase information of the object was obtained by using the continuous phase of the highest frequency.The experimental results show that the RMS error of the measurement is 0.038 mm.The period of dual-frequency heterodyne synthesis did not need to cover the whole field of view,thus breaking the limitation of frequency selection in traditional dual-frequency heterodyne method,which could be used for high accuracy measurement with higher frequency fringes.High frequency fringe can be used for high accuracy measurement even if there is error of phase principal value.